Abstract
In his book Secret Knowledge, David Hockney proposes that the “optical quality” of Flemish art arose around 1420, because artists such as van Eyck then began to use optical devices for accurate projection of subject images onto the canvas. Although Hockney describes Lotto's Man and Wife as the “Rosetta Stone” of his argument, the author's analysis reveals that its perspective structure is incompatible with the logic of local optical projection. Regions that should be geometrically coherent in an optical projection display pronounced distortions, while regions that should be incoherent show no such distortions. Such detailed evidence, as well as the inability of optical projection to capture the effect of windblown garments, is inconsistent with Hockney's claim.